Message Interface Register Sets
1060
SPNU503C – March 2018
Copyright © 2018, Texas Instruments Incorporated
Controller Area Network (DCAN) Module
23.6.3 Message Interface Register 3
The IF3 register set can automatically be updated with received message objects without the need to
initiate the transfer from Message RAM by CPU. The intention of this feature of IF3 is to provide an
interface for the DMA to read packets efficiently.
Table 23-5. Message Interface Register 3
Address
IF3 Register Set
[CAN Base +]
31
16 15
0
0x140
reserved
IF3 Observation
0x144
IF3 Mask 2
IF3 Mask 1
0x148
IF3 Arbitration 2
IF3 Arbitration 1
0x14C
reserved
IF3 Message Control
0x150
IF3 Data A 2
IF3 Data A 1
0x154
IF3 Data B 2
IF3 Data B 1
...
0x160
IF3 Update Enable 2
IF3 Update Enable 1
0x164
IF3 Update Enable 4
IF3 Update Enable 3
0x168
IF3 Update Enable 6
IF3 Update Enable 5
0x16C
IF3 Update Enable 8
IF3 Update Enable 7
The automatic update functionality can be programmed for each message object (see IF3 Update Enable
Register,
).
All valid message objects in Message RAM that are configured for automatic update, will be checked for
active NewDat flags. If such a message object is found, it will be transferred to the IF3 register (if no
previous DMA transfers are ongoing), controlled by IF3 Observation register. If more than one NewDat
flag is active, the message object with the lowest number has the highest priority for automatic IF3 update.
The NewDat bit in the message object will be reset by a transfer to IF3.
If DCAN internal IF3 update is complete, a DMA request is generated. The DMA request stays active until
first read access to one of the IF3 registers. The DMA functionality has to be enabled by setting bit DE3 in
CAN Control register. Please refer to the device datasheet to find out if this DMA source is available.
NOTE:
The IF3 register set can not be used for transferring data into message objects.